Impact apparatus for cutting grooves in roads

ABSTRACT

Apparatus for cutting parallel grooves in roads, particularly concrete roads, to improve the anti-skid properties of the road, comprises a plurality of pneumatic hammer units mounted in line on a frame supported on steerable road wheels, the hammer units being fitted with cutting tools engagable with the road and being operable to reciprocate the cutting tools so as to impart a series of impact blows to the road surface. The road wheels are drivably connected to a motor on the frame, and in operation the wheels are aligned in a direction such that the frame moves transversely or diagonally across the road with the hammer units spaced apart relative to the direction of travel, whereby the hammer units cut parallel grooves in the road surface. The hammer units are inclined at a small angle to the vertical so that the bases of the grooves are inclined downwards in the direction of the flow of traffic on the road, the downstream side of each groove having a sharply defined edge and the upstream edge merging into the uncut road surface between the grooves. The frame is provided with retractable wheels drivably connected to the motor and pneumatic cylinders operable to force the retractable wheels downwards and lift the hammer units and road wheels above the road. In operation of the apparatus, the retractable wheels are parallel to the centre line of the road being cut so that after cutting one band of parallel grooves on the steerable wheels the frame can be moved forwards on the retractable wheels to a position suitable for cutting the next band of grooves without altering the steering angle of the road wheels. The steering mechanism of the road wheels may be continuously adjusted during travel of the frame to cut grooves along a curved path, particularly a curved path having a radial centre on or adjacent the longitudinal centre line of the road upstream of the grooves, which curved grooves have a centering effect on the wheels of vehicles.

[ lMPACT APPARATUS FOR CUTTING GROOVES IN ROADS Ronald Albert William Clark, London, England [75] Inventor:

[73] Assignee: Klarcrete Limited, Redhill, Surrey,

England [22] Filed: May 24, 1972 [21] Appl. No.: 256,437

[30] Foreign Application Priority Data May 28, l97l Great Britain l7868/7l [52] U.S. Cl 299/37, 173/24, l73/25 [51] Int. Cl. E0lc 23/09 [58] Field of Search 299/36-41 [56] References Cited UNITED STATES PATENTS 1,644,582 10/1927 Hargrave 299/37 1,745,100 l/l930 Johnston et al... 299/37 X 2,553,435 5/1951 Briese 299/37 X 2,974,938 3/1961 Lewis 299/39 3,547,492 4/1969 Binger 299/39 Primary ExaminerErnest R. Purser Attorney, Agent, or Firm-Browdy and Neimark [57] ABSTRACT Apparatus for cutting parallel grooves in roads, particularly concrete roads, to improve the anti-skid properties of the road, comprises a plurality of pneumatic hammer units mounted in line on a frame supported on steerable road wheels, the hammer units being fit- Feb. 12, 1974 ted with cutting tools engagable with the road and being operable to reciprocate the cutting tools so as to impart a series of impact blows to the road surface. The road wheels are drivably connected to a motor on the frame, and in operation the wheels are aligned in a direction such that the frame moves transversely or diagonally across the road with the hammer units spaced apart relative to the direction of travel, whereby the hammer units cut parallel grooves in the road surface. The hammer units are inclined at a small angle to the vertical so that the bases of the grooves are inclined downwards in the direction of the flow of traffic on the road, the downstream side of each groove having a sharply defined edge and the upstream edge merging into the uncut road surface between the grooves.

The frame is provided with retractable wheels drivably connected to the motor and pneumatic cylinders operable to force the retractable wheels downwards and lift the hammer units and road wheels above the road. in operation of the apparatus, the retractable wheels are parallel to the centre line of the road being cut so that after cutting one band of parallel grooves on the steerable wheels the frame can be moved forwards on the retractable wheels to a position suitable for cutting the next band of grooves without altering the steering angle of the road wheels. The steering mechanism of the road wheels may be continuously adjusted during travel of the frame to cut grooves along a curved path, particularly a curved path having a radial centre on or adjacent the longitudinal centre line of the road upstream of the grooves, which curved grooves have a centering effect on the wheels of vehicles.

6 Claims, 5 Drawing Figures PATENTED FEB) 2 I974 SHEET 1 BF 2 IMPACT APPARATUS FOR CUTTING GROOVES IN ROADS This invention relates to apparatus for cutting grooves in roads, runways or other pavement surfaces, hereinafter referred to for convenience as roads, in order to increase the frictional resistance between the road surface and the wheels of vehicles, and thereby improve the anti-skid properties of the road surface.

The surfaces of roads, particularly concrete roads, become very smooth when subjected to heavy traffic over a long period, with a resulting decrease in the antiskid properties of the road surface. Moreover in wet weather a thin film of water tends to adhere to the smooth surface of the road and there is then a serious risk of vehicles aqua-planing. It is known to cut narrow grooves in the surface of concrete roads by rotary grinding discs in an attempt to improve the anti-skid properties of the road, but the grinding of concrete is a slow laborious operation requiring copious supplies of coolant and it has only been practicable to cut narrow grooves, usually mm wide and 5 mm deep. Such grooves are too narrow to be effective.

According to the present invention there is provided apparatus for cutting grooves in the surface of a road, comprising a frame, reciprocating means mounted on the frame and fitted with a plurality of cutting tools adapted to engage the road, the reciprocating means being operable to reciprocate the cutting tools so as to impart a series of impact blows to the road surface, and drive means operable to move the frame continuously along a predetermined path on the road, the cutting tools being spaced apart transversely relative to the direction of travel of the frame so that they cut grooves which are spaced apart from one another.

According to the present invention there is also provided a method of cutting grooves in the surface of a road, comprising continuously moving a plurality of reciprocating cutting tools along parallel paths spaced apart on the road surface so as to impart a series of impact blows to the road surface along said paths and cut away the road surface in the paths to form separate parallel grooves in the road surface. The speed of travel of the cutting tools along the paths is preferably low enough to provide grooves of the required depth in one pass of the tools along the paths.

The invention is particularly applicable to the cutting of grooves in concrete roads and enables parallel grooves to be cut much more quickly and easily than is possible with the known grinding process. Moreover due to the fact that the cutting tools are moving continuously over the concrete each impact blow is delivered to a different point on the concrete and there is thus no risk of the tool digging in and causing cracks in the concrete.

The grooves are preferably wide enough to cause the tyre of a vehicle running over each groove to penetrate slightly into the groove and engage against the edge of the groove. The grooves can conveniently be approximately 50 mm. wide and between 3 mm. and 8 mm. deep. The grooves are preferably spaced apart a distance approximately equal or less than the width of the grooves.

Relatively wide grooves have also the advantage that there is little risk of the grooves becoming blocked by debris and dirt, as was frequently the case with the narrow grooves of 5 mm. used hitherto, so that any water on the road is free to drain away through the grooves. Moreover in the event of a sudden rainstorm, wide grooves have sufficient capacity to contain the water until it has time to drain away at the sides of the road, so that water does not remain on the top surface of the road.

The bases of the grooves are preferably inclined downwards relative to the top surface of the road in the general direction of the flow of traffic on the road. Such grooves require substantially less cutting away of the road surface than is the case with flat bottomed grooves having the same depth across the groove.

The grooves may extend transversely or diagonally across the road, and may be straight, curved, or follow a zig-zag line. The grooves may be arcuate and extend across the entire road surface with the radial centres of the grooves in or adjacent the longitudinal centre line of the road and upstream relative to the flow of traffic. Such an arrangement has the desirable property of exerting forces on the wheels of vehicles tending to straighten out the wheels, in addition to providing an anti-skid surface.

The grooves may be arranged in a diamond pattern.-

Such a pattern can be formed by moving two groups of reciprocating cutting tools over the road surface along paths which intersect.

Apparatus for cutting grooves in roads according to the invention will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is an elevation view of the apparatus,

FIG. 2 is a plan view of the apparatus,

FIG. 3 is a sectional view of the top surface of a road cut with grooves by the apparatus of FIGS. 1 and 2, showing the shape of the grooves,

FIG. 4 is a plan view of a road showing the path of travel of the apparatus when cutting straight diagonal grooves in the road, and

FIGS. 5 (a), (b), (c) are plan views of a road on a smaller scale to that of FIG. 4 and showing other patterns of grooves which can be cut by the apparatus of FIGS. 1 and 2.

The apparatus comprises a main frame consisting of two longitudinal beams 10, ll interconnected at the ends thereof by relatively short cross beams 12, 13 four pairs of steerable road wheels 14 arranged one pair at each corner of the frame, two pairs of retractable road wheels 16 arranged one pair at each end of the frame, two lift mechanisms each operable to force a separate pair of the retractable road wheels downwards against the road and thereby lift the adjacent end of the frame and raise the adjacent road wheels 14 above the road, an air-operated motor 18 and power transmission gearing for driving the road wheels 14, 15, and a plurality of pneumatic hammer units 19 mounted on the frame, each hammer unit being operable to reciprocate a cutting tool 20 mounted on the hammer unit and engaged with the road surface so as to impart a series of impact blows to the road surface.

Each pair of road wheels 14 are secured on an axle '25 rotatably mounted in the arms of a yoke 26 on the lower end of a vertical column 27 which is pivotally mounted in the associated cross beam 12 or 13. The columns 27 for the four pairs of wheels extend upwards above the cross beams 12, 13 and are coupled together by steering mechanism.

The steering mechanism comprises a steering rod extending along one side of the apparatus and pivotally connected at the ends thereof to the outer ends of arms 31 secured to the upper ends of the two columns 27 on the adjacent side of the apparatus, and two rods 32 at opposite ends of the apparatus each pivotally connected at the ends thereof to the outer ends of arms 33 secured to the upper ends of the two columns 27 at the adjacent end of the apparatus. The arms 31, 33 are arranged so that the columns 27 all pivot through the same angle in response to axial movement of the steering rod 30 and the road wheels 14 are all aligned for travel in the same direction at any particular setting of the steering rod 30. The axial position of the steering rod 30 is controlled by a pneumatic cylinder 36 having a piston (not shown) connected to a piston rod 37 which projects from one end of the cylinder and is pivotally connected to one end of a lever 38, the other end of which is pivotally connected to the steering rod 30. The end of the cylinder 36 remote from the piston rod is pivotally connected to a bracket 39 on the frame and the centre portion of the lever 38 is also pivotally connected to a bracket 40 on the frame.

Each retractable wheel 16 is mounted on the lower end of a cranked lever 45, the cranked portion of which is pivotally mounted at 46 to the adjacent longitudinal beam 10 or 11. The upper ends of the two levers at each end of the frame are interconnected by a bar 47 (FIG. 2), the centre of which is pivotally connected to the outer end of the piston rod 48 of a pneumatic cylinder 49. The end of the cylinder 49 remote from the piston rod is pivotally connected to a bracket 50 on the frame of the apparatus. The two cylinders 49 are arranged so that expansion of the cylinders will cause the levers 45 to turn about their pivots 46 in a direction to raise the wheels 16 to the retracted positions shown in full lines in FIG. 1, and contraction of the cylinders lowers the wheels to the positions shown in broken lines. In FIG. 1 the cylinders 49 are shown in full lines in the contracted position, and the levers 45 are shown in full lines in the retracted positions (the upper ends of the levers 45 being broken away) and in broken lines in the fully lowered positions.

The output shaft of the motor 18 is drivably connected by a belt and pulley drive to a shaft 56 which extends almost the full length of the apparatus and is mounted in bearings supported on brackets 57 on the frame of the apparatus. Power is transmitted from the shaft 56 to one pair of road wheels 14 at each end of the apparatus by worm reduction gearing 58 mounted in housings 59 supported on the cross beams 12, further worm reduction gearing 60 mounted in housings 61 supported on the upper ends of the steering columns 27 for angular movement therewith, and belt and pulley drives 62 between the output elements of gearing 60 and the axles 25. Power is transmitted from the shaft 56 to two of the retractable wheels 16 by worm reduction gearing 63 and belt and pulley drives 64. The gearing and the belt and pulley drives are conventional and their construction and operation will be apparent to one skilled in the art from an inspection of FIG. 1.

Each hammer unit 19 comprises a cylinder block having a bore closed at the ends thereof, a piston reciprocable in the cylinder bore, the piston having a piston rod extending as a close sliding fit through an aperture in an end wall of the bore in the cylinder block, and valve means operable to feed compressed air alternately to each end of the cylinder bore while exhausting the air from the opposite end so as to continuously reciprocate the piston in the cylinder bore. Such hammer units are well known in the art and their construction has not therefore been illustrated in the drawings.

The hammer units in the apparatus of the invention have their cylinder blocks mounted between the longitudinal beams l0, 11 with their piston rods 71 extending downwards below the beams 10, 11, the cylinder blocks 70 extending above the beams 10, 11, and plates 72 are secured to the upper ends of the cylinder blocks, the ends of the plates 72 projecting across the beams 10, 11. The cylinder blocks are angularly adjustable between a vertical position and an inclined position as shown in FIG. 1, and are securely bolted to the beams 10, 11 in the selected positions. All the hammer units are adjusted to the same angle of inclination by slackening the bolts securing each cylinder block to the beams 10, 11, forcing wedges between the top surfaces of the beams 10, 11 and the plate 72 so that the cylinder block takes up the angle of inclination of the wedges, and then tightening the bolts securing the cylinder block to the beams 10, 11.

The cutting tools 20 are secured to the lower ends of the piston rods 71 of the hammer units, the undersides of the tools being formed with teeth the cutting edges of which extend radially outwards from the axis of the tool. In each hammer unit, the piston, piston rod and cutting tool are free to move angularly about the axis of the cylinder bore.

Compressed air for operating the hammer units 19, the air motor 18, and the cylinders 36, 49 is supplied from a common reservoir tank (not shown) mounted on the frame of the apparatus.

In operation, the apparatus is positioned at one end of a path on a road along which parallel grooves are to be cut, the apparatus being arranged with the beams 10, 11 extending transversely or obliquely across the path, the steering mechanism is adjusted by the cylinder 36 to align the road wheels 14 in the direction of the path, and the wheels 16 are retracted by contraction of the cylinders 49 so that the apparatus is supported on the wheels 14. The wheels 14 are then driven by the motor 18 so as to propel the apparatus along the path, and the cutting tools 20 are reciprocated by the hammer units so that they impart a series of impact blows to the road surface. Each tooth on the cutting tools strikes the road surface at a different point at the end of each successive stroke of the tool due to the fact that the apparatus is moving continuously along the path and also due to the fact that each cutting tool together with piston and piston rod of its hammer unit is free to rotate about the axis of the hammer unit. The apparatus is driven at a slow enough speed to ensure that the grooves of the required depth are cut in one pass of the apparatus, that is by movement of the apparatus once along the length of the path along which the grooves are to be cut. At the end of the path, the retractable wheels 16 are forced downwards by operation of the two cylinders 49 so as to lift the frame of the apparatus and raise the wheels 14 and cutting tools 20 above the ground. The wheels 16 may then be driven by the motor 18 to propel the apparatus to another site.

In the case of a concrete road, it is believed that the impact blows have the effect of compressing the small portion of concrete underlying each tooth of the cutting tools, and that the energy stored in the compressed concrete causes a rebound of the concrete which results in the concrete then being under tensile stress. As is well known, concrete has a high resistance to compression but a low resistance to tensile stress. A small degree of crushing of the concrete takes place during compression, but the cutting action of the tools is caused mainly by small particles of the concrete breaking away under tensile stress. The cutting action is thus due more to the speed and frequency of the impact blows rather than to the actual thrust exerted on the cutting tools.

FIG. 3 illustrates in cross-section the grooves cut by the apparatus of FIGS. 1 and 2 in a road on which traffic flows in the direction indicated by the arrow. The apparatus is driven along a path which extends transversely or obliquely across the road and the apparatus is arranged so that the cutting tools are inclined downwardly in the upstream direction of traffic flow. The apparatus is driven at a speed at which the tools penetrate to a depth such that each groove has a sharply defined downstream edge 75, but the upstream edge portion 76 of the groove merges smoothly into the uncut road surface 77 between the grooves.

FIG. 4 shows the path of travel of the apparatus of FIGS. 1 and 2 when cutting diagonal grooves across a road. The apparatus, shown in block form, is first supported on its retractable wheels 16 at position A on one side of the road, with the beams 10, 11 parallel to the side edge of the road and the cross beam 12 at the downstream end relative to the traffic flow. The wheels 14 are aligned with the path A-B which extends obliquely across the road in the upstream direction, the wheels 16 are then retracted so that the apparatus is supported on the wheels 14, and the wheels 14 driven by the motor 18 while the hammer units reciprocate the cutting tools against the road, so that the apparatus travels along path A-B while cutting parallel grooves in the road. When the apparatus reaches position B on the opposite side of the road, the wheels 16 are forced downwards to lift the wheels 14 and cutting tools off the ground. The wheels 16, which are aligned with the side edge of the road, are then driven by the motor 18 to propel the apparatus in the downstream direction to a position C in which the upstream cutting tool 20 is immediately downstream of the downstream groove cut in the road. At position C, the wheels 16 are again retracted so that the apparatus rests on wheels 14 which are then driven in the opposite direction to propel the apparatus across the road in the downstream direction along path C-D parallel to path A-B, while the hammer units out parallel grooves in the road. In this way the whole length of a road can be cut with parallel grooves extending across the full width of the road.

A diamond pattern of grooves as shown in FIG. 5 (a) may be cut in a road by first cutting diagonal grooves as shown in FIG. 4 and then cutting further diagonal grooves which interesect the first grooves. The diagonal grooves can of course be cut at any desired angle relative to the longitudinal centre line of the road.

The curved pattern of grooves shown in FIG. 5 (b) may be obtained by steering the apparatus around a curved path the radial centre of which is located on the centre line of the road, while cutting grooves in the road.

For this purpose, compressed air may be fed at a controlled rate to the cylinder 36 to continuously steer the apparatus around the curved path.

The pattern shown in FIG. 5 (0) may be obtained by alternately expanding and contracting the steering cylinder 36 while the motor 18 propels the apparatus across the road and the hammer units cut grooves in the road. Valve means for controlling supply of air to the cylinder 36 for this purpose may be of any suitable construction known in the art.

The apparatus described above is particularly suitable for cutting grooves in concrete roads which cannot otherwise be cut except by grinding which has the previously mentioned disadvantages. The apparatus can however be used to cut parallel grooves in bitumen or other pavement surfaces much more quickly and easily than has hitherto been possible.

In another construction of apparatus according to the invention, the hammer units fitted with cutting tools are mounted on a frame which is movable along rails or tracks on a base adapted to be mounted on a road to be cut, the hammer units being spaced apart along a line normal or oblique to the direction of travel of the frame along the rails, and drive means are provided for moving the frame continuously along the rails at a speed slow enough to enable the hammer units to cut parallel grooves in the road.

I claim:

1. Apparatus for cutting grooves in the surface of a road, comprising a frame having steerable road wheels adapted to run on the road to be cut, reciprocating means mounted on the frame and fitted with a plurality of cutting tools which are spaced apart transversely relative to the direction of travel of the frame, the reciprocating means being operable to reciprocate the cutting tools against the road surface so as to impart a series of impact blows thereto, and drive means comprising a motor mounted on the frame and drivably connected to at least one of the road wheels, said drive means being operable to move the frame continuously along a predetermined path on the road at a speed which is slow enough to ensure that the cutting tools cut spaced apartgrooves in the road surface.

2. Apparatus as claimed in claim 1, wherein the steerable road wheels are interconnected by steering mechanism operable continuously during travel of the frame to steer the frame around a curved path.

3. Apparatus as claimed in claim 1, including retractable wheels, and lifting means operable to force the retractable wheels downwards against the road so as to lift the frame and raise the road wheels above the ground, whereby the frame may be moved in the direction of alignment of the retractable wheels.

4. Apparatus as claimed in claim 3, wherein each end of the frame is provided with steerable road wheels and retractable wheels, and separate lifting means are provided for the retractable wheels at each end of the frame, whereby the frame may be supported at one end on steerable road wheels and at the other end on retractable wheels to permit alignment of the frame in any particular direction.

5. Apparatus for cutting grooves in the surface of a road, comprising a frame, cutting means mounted on the frame and fitted with a plurality of cutting tools adapted to engage the road, and drive means operable to move the frame continuously at a slow speed along a predetermined path on the road, said cutting tools being spaced transversely relative to the direction of travel of the frame so that the cutting tools cut grooves in the road surface, wherein said cutting tools are arranged so that the bases of the grooves cut in the road surface by said tools are inclined relative to the surface of the road.

6. Apparatus for cutting grooves in the surface of a road, comprising a frame having road wheels adapted to support the frame on the road, a plurality of power driven hammer units mounted on the frame and operable to reciprocate cutting tools into engagement with the road surface so as to impart a series of impace blows thereto, said cutting tools being spaced apart transversely relative to the direction of travel of the frame on said road wheels, and drive means comprising a motor mounted on the frame and drivably connected to at least one of the road wheels, said drive means being operable to propel the apparatus across the road at a continuous speed which is slow enough to ensure that the cutting tools cut spaced apart grooves in the road surface, wherein said hammer units are arranged so that the cutting tools reciprocate along axes which are inclined to the vertical in a direction transverse to the direction of travel of the frame so as to cut grooves UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION patent 3,791,599 Dated February 12, 1974 Roriald Albert William Clarke Inventor (s It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On the Title page, at [75] the inventor's name should read:

--Ronald Albert William Clarke-- Signed'and sealed this 22nd day'of' October 1974.

(SEAL) Attest:

McCOY M. GIBSON JR. c. MARSHALL DANN Attesting Officer Commissioner of Patents -ORM PO- 050 (10-69) USCOMM-DC scan-Pas U. 5. GOVERNMENT PRINTING OFFICE I 0-3664 

1. Apparatus for cutting grooves in the surface of a road, comprising a frame having steerable road wheels adapted to run on the road to be cut, reciprocating means mounted on the frame and fitted with a plurality of cutting tools which are spaced apart transversely relative to the direction of travel of the frame, the reciprocating means being operable to reciprocate the cutting tools against the road surface so as to impart a series of impact blows thereto, and drive means comprising a motor mounted on the frame and drivably connected to at least one of the road wheels, said drive means being operable to move the frame continuously along a predetermined path on the road at a speed which is slow enough to ensure that the cutting tools cut spaced apart grooves in the road surface.
 2. Apparatus as claimed in claim 1, wherein the steerable road wheels are interconnected by steering mechanism operable continuously during travel of the frame to steer the frame around a curved path.
 3. Apparatus as claimed in claim 1, including retractable wheels, and lifting means operable to force the retractable wheels downwards against the road so as to lift the frame and raise the road wheels above the ground, whereby the frame may be moved in the direction of alignment of the retractable wheels.
 4. Apparatus as claimed in claim 3, wherein each end of the frame is provided with steerable road wheels and retractable wheels, and separate lifting means are provided for the retractable wheels at each end of the frame, whereby the frame may be supported at one end on steerable road wheels and at the other end on retractable wheels to permit alignment of the frame in any particular direction.
 5. Apparatus for cutting grooves in the surface of a road, comprising a frame, cutting means mounted on the frame and fitted with a plurality of cutting tools adapted to engage the road, and drive means operable to move the frame continuously at a slow speed along a predetermined path on the road, said cutting tools being spaced transversely relative to the direction of travel of the frame so that the cutting tools cut grooves in the road surface, wherein said cutting tools are arranged so that the bases of the grooves cut in the road surface by said tools are inclined relative to the surface of the road.
 6. Apparatus for cutting grooves in the surface of a road, comprising a frame having road wheels adapted to support the frame on the road, a plurality of power driven hammer units mounted on the frame and operable to reciprocate cutting tools into engagement with the road surface so as to impart a series of impace blows thereto, said cutting tools being spaced apart transversely relative to the direction of travel of the frame on said road wheels, and drive means comprising a motor mounted on the frame and drivably connected to at least one of the road Wheels, said drive means being operable to propel the apparatus across the road at a continuous speed which is slow enough to ensure that the cutting tools cut spaced apart grooves in the road surface, wherein said hammer units are arranged so that the cutting tools reciprocate along axes which are inclined to the vertical in a direction transverse to the direction of travel of the frame so as to cut grooves the bases of which are inclined to the horizontal. 